Control system of electrical thermostat and the system thereof

ABSTRACT

A control method of an electrical thermostat that includes an operating heater heating wax so as to operate an operating valve that may be disposed to close a coolant passage according to an exemplary embodiment of may include detecting a coolant temperature of coolant circulating a coolant passage, determining whether the coolant temperature may be included in a predetermined heating temperature range, performing a coolant heating mode by supplying a predetermined level of power to the operating heater for a predetermined time, if the coolant temperature may be within the heating temperature range, and stopping the coolant heating mode in a condition that the operating valve may be closed.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to Korean Patent Application No.10-2012-0115640 filed on Oct. 17, 2012, the entire contents of which isincorporated herein for all purposes by this reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a control method of an electricalthermostat and the system thereof that changes a passage of a coolantdepending on the temperature of the coolant and actively controls thecoolant temperature to prevent overheating thereof.

2. Description of Related Art

A thermostat for a vehicle is disposed between an engine and a radiator,is automatically opened/closed by the temperature variation of coolantto adjust the flow rate of the coolant, and therefore the temperature ofthe coolant is controlled in a predetermined range.

A mechanical thermostat expands wax depending on the temperature of thecoolant, and the expanding force of the wax makes a piston move thevalve of the thermostat.

The mechanical thermostat is operated in a predetermined opening/closingtemperature of the coolant to open/close the valve only in apredetermined temperature condition, and therefore the mechanicalthermostat does not actively move against changes of the drivingcircumstances of the vehicle.

Accordingly, an electrical thermostat has been introduced to complementsthe drawback of the mechanical thermostat, and the electrical thermostatis operated to sustain the coolant temperature in an optimized range.

The electrical thermostat actively controls the coolant temperature ofthe engine according to the driving circumstances such as the load levelof the vehicle to sustain the optimized coolant temperature, and theelectrical thermostat can improve fuel consumption efficiency and reduceexhaust gas.

A drive portion that is a temperature sensitive type and is electricallycontrolled has been applied to open or close the valve of a thermostat,and the drive portion includes wax, semi-fluid, a rubber piston, aback-up plate, and a main piston.

Here, a coolant temperature is low before an engine is started, andtherefore fuel consumption and harmful exhaust gas can be increased bythe low temperature coolant. Accordingly, the arts for quickly raisingthe coolant temperature have been researched.

The information disclosed in this Background of the Invention section isonly for enhancement of understanding of the general background of theinvention and should not be taken as an acknowledgement or any form ofsuggestion that this information forms the prior art already known to aperson skilled in the art.

BRIEF SUMMARY

Various aspects of the present invention are directed to providing acontrol method of an electrical thermostat and the system thereof havingadvantages of quickly raising the coolant temperature after an engine isstarted.

In an aspect of the present invention, a control method of an electricalthermostat that may include an operating heater configured to heat waxso as to operate an operating valve that is disposed to close a coolantpassage, may include detecting a coolant temperature of coolant flowingalong the coolant passage, determining whether the coolant temperatureis may include d in a predetermined heating temperature range,performing a coolant heating mode by supplying a predetermined level ofpower to the operating heater for a predetermined time when the coolanttemperature is within the predetermined heating temperature range, andstopping the coolant heating mode when the operating valve is closed.

The predetermined heating temperature range is set to be lower than anoperating minimum temperature.

The control method of the electrical thermostat may further includeselecting the predetermined level of the power and the predeterminedtime that are supplied to the operating heater from a map data accordingto the coolant temperature that is may include d in the heatingtemperature range, and supplying the operating heater with thepredetermined level of the power for the predetermined time that isselected from the map data.

The predetermined level is a PWM duty and the PWM duty is selected from0 to 100% range.

The control method of the electrical thermostat may further includedetermining whether the coolant temperature is higher than the operatingminimum temperature for operating the operating valve, and performing avalve operating control for opening the operating valve when the coolanttemperature is higher than the operating minimum temperature.

The control method of the electrical thermostat may further includeincreasing a PWM duty when the coolant temperature is higher than atarget temperature.

The control method of the electrical thermostat may further includesetting the PWM duty to 100% when it is determined that an absolutevalue between the target temperature and the coolant temperature islarger than an upper allowance value.

The control method of the electrical thermostat may further includedecreasing a PWM duty when the coolant temperature is lower than atarget temperature.

The control method of the electrical thermostat may further includesetting the PWM duty to 0% when it is determined that an absolute valuebetween the target temperature and the coolant temperature is lower thana lower allowance value.

The coolant heating mode is stopped before the operating valve isopened.

In another aspect of the present invention, a control system of anelectrical thermostat that may include an operating heater configured toheat wax so as to operate an operating valve that is disposed to close acoolant passage, may include a temperature detector that detects acoolant temperature of coolant flowing along the coolant passage, apower supply portion that supplies the operating heater with power, anda control portion that controls the power that is supplied to theoperating heater from the power supply portion by using a temperaturesignal that is transferred from the temperature detector, wherein thecontrol portion determines whether the coolant temperature is within apredetermined heating temperature range, controls the power supplyportion to supply the operating heater with a predetermined level ofpower for a predetermined time when the coolant temperature is within aheating temperature range, and heats the coolant when the operatingvalve is closed.

The heating temperature range is set to be lower an operating minimumtemperature.

The control portion selects the predetermined level of power and thepredetermined time that are supplied to the operating heater from a mapdata according to the coolant temperature that is may include d in theheating temperature range and supplies the operating heater with thepredetermined level of power for the predetermined time that is selectedfrom the map data.

The predetermined level is a PWM duty and the PWM duty is selected from0 to 100% range.

The control portion determines whether the coolant temperature is higherthan the operating minimum temperature for operating the operatingvalve, and performs a valve operating control for opening the operatingvalve when the coolant temperature is higher than the operating minimumtemperature.

The control portion increases a PWM duty when the coolant temperature ishigher than a target temperature.

The control portion sets the PWM duty to 100% when it is determined thatan absolute value between the target temperature and the coolanttemperature is larger than an upper allowance value.

The control portion decreases a PWM duty when the coolant temperature islower than a target temperature.

The control portion sets the PWM duty to 0% when it is determined thatan absolute value between the target temperature and the coolanttemperature is lower than a lower allowance value.

The control portion stops the coolant heating mode before the operatingvalve is opened.

The control method of an electrical thermostat and the system thereofaccording to an exemplary embodiment of the present invention suppliesan operating heater with electric power to raise the coolant temperaturein a condition that the operating valve is maintained to be closed, ifthe coolant temperature is included in a heating temperature range.

Further, because an operating heater of a thermostat is used without aseparate heating device, the cost is saved.

The methods and apparatuses of the present invention have other featuresand advantages which will be apparent from or are set forth in moredetail in the accompanying drawings, which are incorporated herein, andthe following Detailed Description, which together serve to explaincertain principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a system having an electricalthermostat according to an exemplary embodiment of the presentinvention.

FIG. 2 is a flowchart showing a control method of an electricalthermostat according to an exemplary embodiment of the presentinvention.

FIG. 3 is a partial cross-sectional view of an electrical thermostatthat is disposed on a coolant line of an engine according to anexemplary embodiment of the present invention.

FIG. 4 is a graph showing an operational characteristic of an electricalthermostat according to an exemplary embodiment of the presentinvention.

It should be understood that the appended drawings are not necessarilyto scale, presenting a somewhat simplified representation of variousfeatures illustrative of the basic principles of the invention. Thespecific design features of the present invention as disclosed herein,including, for example, specific dimensions, orientations, locations,and shapes will be determined in part by the particular intendedapplication and use environment.

In the figures, reference numbers refer to the same or equivalent partsof the present invention throughout the several figures of the drawing.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments of thepresent invention(s), examples of which are illustrated in theaccompanying drawings and described below. While the invention(s) willbe described in conjunction with exemplary embodiments, it will beunderstood that the present description is not intended to limit theinvention(s) to those exemplary embodiments. On the contrary, theinvention(s) is/are intended to cover not only the exemplaryembodiments, but also various alternatives, modifications, equivalentsand other embodiments, which may be included within the spirit and scopeof the invention as defined by the appended claims.

An exemplary embodiment of the present invention will hereinafter bedescribed in detail with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of a system having an electricalthermostat according to an exemplary embodiment of the presentinvention.

Referring to FIG. 1, a system having an electrical thermostat includes acoolant temperature detector 9, an engine 10, an electrical thermostat11, a power supply portion 12, a data storage portion 13, and a controlportion 14.

The coolant temperature detector 9 detects the temperature of thecoolant circulating the engine 10, and transfers the detectedtemperature to the control portion 14. And, the control portion 14detects driving information such as RPM, load, and vehicle speed of theengine 10.

The control portion 14 selects data from the data storage portion 13according to the driving information and the coolant temperature andcontrols the power supply portion 12 depending on the selected data toactively control the electrical thermostat 11.

The control portion 14 controls the power that is supplied to theoperating heater (105 of FIG. 3) of the electrical thermostat 11 throughthe power supply portion 12. Accordingly, the coolant of the engine iscirculated to the radiator at an appropriate time by actively opening orclosing the operating valve 200 of the electrical thermostat 11.

if it is determined that the temperature of the coolant circulating theengine 10 is within a heating temperature range that is a predeterminedlow value, the control portion 14 operates the operating heater (105 ofFIG. 3) to perform a coolant heating mode in an exemplary embodiment ofthe present invention.

The coolant heating mode is characterized in that the power is suppliedto the operating heater 105 and the operating valve (200 of FIG. 3)maintains its closed condition. If the operating valve 200 is opened bythe heater 105, the temperature of the coolant is not raised, becausethe coolant is cooled by the radiator (150 of FIG. 3).

Further, the heating temperature range that the coolant heating mode isperformed can range from −40 to 40 Celsius decrees, and the heatingtemperature range can be varied depending on the design specification.

The power that is supplied to the operating heater 105 has a PWM dutytype and it is controlled in a level ranging from 0 to 100%.

A vehicle is tested in advance, wherein the power level and power supplytime that are supplied to the operating heater 105 are predetermineddepending on the coolant temperature and the driving information of thetested vehicle, and the predetermined power level and power supply timeare stored in the data storage portion 13 as a map data type.

The control portion 14 detects the coolant temperature and the drivinginformation, selects the data from the map data that is stored in thedata storage portion 13 depending on the detected information, andcontrols the level and the supply time of the power that is supplied tothe operating heater 105 based on the selected data.

The coolant heating mode is performed in a condition that the operatingvalve 200 is closed so as to effectively raise the temperature of thecoolant in an exemplary embodiment of the present invention.

FIG. 2 is a flowchart showing a control method of an electricalthermostat according to an exemplary embodiment of the presentinvention.

Referring to FIG. 2, a starting of an engine is detected in a S205. Acoolant temperature, a RPM, a load, and a vehicle speed are detected ina S210.

It is determined whether the coolant temperature is larger than apredetermined max value in a S215. If the coolant temperature is largerthan that, a S260 is performed, wherein the PWM duty that is supplied tothe operating heater 105 becomes 100%. If the coolant temperature isless than that, a S220 is performed. The max value of the coolanttemperature can be 120 Celsius degrees.

It is determined whether the coolant temperature is in the heatingtemperature range in a S220. The heating temperature range can be avalue that is selected from −40 to +40 Celsius degrees. Here, theheating temperature range is set to be lower than an operating minimumtemperature (for example, 60 Celsius degrees) that the operating valve200 starts to be operated.

If the coolant temperature is not within the heating temperature range,it is determined whether the coolant temperature is larger than theoperating minimum temperature of the electric thermostat 11 in a S225.The operating minimum temperature can be +60 Celsius degrees.

More particularly, if it is determined that the coolant temperature isless than 40 Celsius degrees (heating temperature range), the coolantheating mode is performed in the S265, and if it is determined that thecoolant temperature is larger than 60 Celsius degrees (operating mintemperature), the S230 is performed, and if it is determined that thecoolant temperature ranges from 40 to 60 Celsius degrees (no operatingrange), the S270 is performed.

The coolant temperature, the RPM, and the load of an engine, and thevehicle speed are detected in the S230, and the PWM duty that issupplied to the operating heater 105 is controlled according to thedetected information.

A real coolant temperature is compared to a target temperature in aS240, it is determined whether the coolant temperature is higher thanthe target temperature in a S245, and if it is higher that, the PWM dutyvalue % that is supplied to the heater 105 is raised in a S250.

It is determined whether the absolute value between the targettemperature and the coolant temperature is larger than an upper sideallowance value in a S255.

The upper side allowance value is hysteresis value, if the targettemperature value ranges within 100±5, the upper side allowance value is5 and a lower side allowance value is 5. The upper side allowance valueand the lower side allowance value can be varied according to the designspecification.

If it is determined that the coolant temperature is less than the targettemperature in a S275, the PWM duty value that is supplied to theoperating heater 105 is decreased in a S280. And, it is determinedwhether the difference between the target temperature and the coolanttemperature is less than the lower side allowance value in a S285.

If it is NO in the S255 and the S285, a S245 and a S275 are respectivelyperformed, if it is Yes in the S255 and the S285, a S260 and a S290 arerespectively performed.

The current level that is supplied to the operating heater 105 iscontrolled in a S270 in an exemplary embodiment of the presentinvention. As described above, if the coolant temperature is within theheating temperature range, the level and the supply time of the PWM dutythat is supplied to the operating heater are selected from a map data.

That is, if the coolant temperature is within the heating temperaturerange, a predetermined level of power is supplied to the operatingheater 105 for a predetermined time such that the coolant temperature isquickly raised.

The predetermined time and the predetermined level are made from thetest result to be arranged in a map table, and the map table ismemorized in the data storage portion 13.

FIG. 3 is a partial cross-sectional view of an electrical thermostatthat is disposed on a coolant line of an engine according to anexemplary embodiment of the present invention.

Referring to FIG. 1, an engine includes a radiator 150, a coolant outlet160 of an engine, a coolant inlet 170 of an engine, and a thermostat100.

The thermostat 100 includes a thermostat case 137, and a first passage155 is formed to be connected to the radiator 150, a second passage 165is formed to be connected to the coolant outlet 160, and a third passage175 is connected to the coolant inlet 170 in the thermostat case 137.

A coolant pump in an exemplary embodiment of the present invention isdisposed between the third passage 175 and the coolant inlet 170 tocirculate coolant from the thermostat 100 to the engine.

As shown in drawings, the first passage 155 is formed at an upper side,the second passage 165 is formed at a lower side, and the third passage175 is formed between the first and second passages 155 and 165.

A joining space 139 is formed in the thermostat case 137 to be connectedto the first passage 155, the second passage 165, and the third passage175, and a valve body 125 is disposed in the joining space 139.

A first valve 200 is integrally formed at an upper end portion of thevalve body 125 to selectively close the first passage 155, and a secondvalve 205 is integrally formed at a lower end portion of the valve body125 to selectively close the second passage 165. Further, a valve O-ring130 is mounted along an exterior circumference of the first valve 200 tocontact the interior circumference of the first passage 155.

A main spring 145 is disposed inside the thermostat case 137, and anupper end portion of the main spring 145 elastically supports the lowerend portion of the first valve 200 in an upper direction, and a lowerend portion of the main spring 145 is supported by an inner side of thethermostat case 137.

The main spring 145 has a coil spring structure, and the valve body isinserted into the coil of the main spring 145 except the first valve 200and the part that that is inserted into the second passage 165.

Further, a mounting space is formed along a central portion of the valvebody 125 from an upper end side to a lower end side, and a drive portionthat moves the valve body 125 is inserted into the mounting space 215.

The drive portion includes a piston support portion 225, a piston guide127, a main piston 120, a back-up plate 149, a rubber piston 148, asemi-fluid 147, a diaphragm 115, wax 110, a wax case 135, and anoperating heater 105, wherein the operating heater 105 is electricallyconnected to a connector 140.

The piston support portion 225 is formed at a central portion of thesecond valve (by-pass valve) 205 that is formed at a lower end portionof the valve body 125.

FIG. 4 is a graph showing an operational characteristic of an electricalthermostat according to an exemplary embodiment of the presentinvention.

Referring to FIG. 4, a horizontal axis denotes an elapsed time afterpower is supplied to the operating heater 105, and a vertical axisdenotes a height that the operating valve 200 is lifted.

More particularly, a height that the operating valve 200 is openedaccording to the elapsed time after a 12 voltage power is supplied tothe valve 200 in a condition that a coolant temperature is Celsius 70degrees, a height that the operating valve 200 is opened according tothe elapsed time after a 12 voltage power is supplied to the valve 200in a condition that a coolant temperature is Celsius 75 degrees, aheight that the operating valve 200 is opened according to the elapsedtime after a 12 voltage power is supplied to the valve 200 in acondition that a coolant temperature is Celsius 80 degrees, a heightthat the operating valve 200 is opened according to the elapsed timeafter a 12 voltage power is supplied to the valve 200 in a conditionthat a coolant temperature is Celsius 85 degrees, a height that theoperating valve 200 is opened according to the elapsed time after a 12voltage power is supplied to the valve 200 in a condition that a coolanttemperature is Celsius 90 degrees, and a height that the operating valve200 is opened according to the elapsed time after a 12 voltage power issupplied to the valve 200 in a condition that a coolant temperature isCelsius 95 degrees are shown on lines.

And, when the coolant temperature is 60 Celsius degrees, after itelapses 60 seconds, the operating valve 200 can be opened, when thecoolant temperature is 50 Celsius degrees, after it elapses 65 seconds,the operating valve 200 can be opened, and when the coolant temperatureis 40 Celsius degrees, after it elapses 70 seconds, the operating valve200 can be opened. Also, when the coolant temperature is 30 Celsiusdegrees, after it elapses 75, the operating valve 200 can be opened.

As described above, when the coolant temperature is included in aheating temperature range (−40 to 40 Celsius degrees), the power that issupplied to the operating heater 105 is turned off before the operatingvalve 200 is moved. Accordingly, because the power is supplied to theoperating heater 105 only when the operating valve 200 is closed, thecoolant temperature is quickly raised.

In an exemplary embodiment of the present invention, there is a slightdifference between A≦B and A<B. But, two above cases are applied only tounderstand the invention, and therefore it is understood that two aboveexpressions contain same significance.

For convenience in explanation and accurate definition in the appendedclaims, the terms “upper”, “lower”, “inner” and “outer” are used todescribe features of the exemplary embodiments with reference to thepositions of such features as displayed in the figures.

The foregoing descriptions of specific exemplary embodiments of thepresent invention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteachings. The exemplary embodiments were chosen and described in orderto explain certain principles of the invention and their practicalapplication, to thereby enable others skilled in the art to make andutilize various exemplary embodiments of the present invention, as wellas various alternatives and modifications thereof. It is intended thatthe scope of the invention be defined by the Claims appended hereto andtheir equivalents.

What is claimed is:
 1. A control method of an electrical thermostat thatincludes an operating heater configured to heat wax so as to operate anoperating valve that is disposed to close a coolant passage, comprising:detecting a coolant temperature of coolant flowing along the coolantpassage; determining whether the coolant temperature is included in apredetermined heating temperature range; performing a coolant heatingmode by supplying a predetermined level of power to the operating heaterfor a predetermined time when the coolant temperature is within thepredetermined heating temperature range; and stopping the coolantheating mode when the operating valve is closed.
 2. The control methodof the electrical thermostat of claim 1, wherein the predeterminedheating temperature range is set to be lower than an operating minimumtemperature.
 3. The control method of the electrical thermostat of claim1, further including: selecting the predetermined level of the power andthe predetermined time that are supplied to the operating heater from amap data according to the coolant temperature that is included in theheating temperature range; and supplying the operating heater with thepredetermined level of the power for the predetermined time that isselected from the map data.
 4. The control method of the electricalthermostat of claim 3, wherein the predetermined level is a PWM duty andthe PWM duty is selected from 0 to 100% range.
 5. The control method ofthe electrical thermostat of claim 2, further including: determiningwhether the coolant temperature is higher than the operating minimumtemperature for operating the operating valve; and performing a valveoperating control for opening the operating valve when the coolanttemperature is higher than the operating minimum temperature.
 6. Thecontrol method of the electrical thermostat of claim 5, furtherincluding: increasing a PWM duty when the coolant temperature is higherthan a target temperature.
 7. The control method of the electricalthermostat of claim 6, further including: setting the PWM duty to 100%when it is determined that an absolute value between the targettemperature and the coolant temperature is larger than an upperallowance value.
 8. The control method of the electrical thermostat ofclaim 5, further including: decreasing a PWM duty when the coolanttemperature is lower than a target temperature.
 9. The control method ofthe electrical thermostat of claim 8, further including: setting the PWMduty to 0% when it is determined that an absolute value between thetarget temperature and the coolant temperature is lower than a lowerallowance value.
 10. The control method of the electrical thermostat ofclaim 1, wherein the coolant heating mode is stopped before theoperating valve is opened.
 11. A control system of an electricalthermostat that includes an operating heater configured to heat wax soas to operate an operating valve that is disposed to close a coolantpassage, comprising: a temperature detector that detects a coolanttemperature of coolant flowing along the coolant passage; a power supplyportion that supplies the operating heater with power; and a controlportion that controls the power that is supplied to the operating heaterfrom the power supply portion by using a temperature signal that istransferred from the temperature detector, wherein the control portiondetermines whether the coolant temperature is within a predeterminedheating temperature range, controls the power supply portion to supplythe operating heater with a predetermined level of power for apredetermined time when the coolant temperature is within a heatingtemperature range, and heats the coolant when the operating valve isclosed.
 12. The control system of the electrical thermostat of claim 11,wherein the heating temperature range is set to be lower an operatingminimum temperature.
 13. The control system of the electrical thermostatof claim 11, wherein the control portion selects the predetermined levelof power and the predetermined time that are supplied to the operatingheater from a map data according to the coolant temperature that isincluded in the heating temperature range and supplies the operatingheater with the predetermined level of power for the predetermined timethat is selected from the map data.
 14. The control system of theelectrical thermostat of claim 13, wherein the predetermined level is aPWM duty and the PWM duty is selected from 0 to 100% range.
 15. Thecontrol system of the electrical thermostat of claim 12, wherein thecontrol portion determines whether the coolant temperature is higherthan the operating minimum temperature for operating the operatingvalve, and performs a valve operating control for opening the operatingvalve when the coolant temperature is higher than the operating minimumtemperature.
 16. The control system of the electrical thermostat ofclaim 15, wherein the control portion increases a PWM duty when thecoolant temperature is higher than a target temperature.
 17. The controlsystem of the electrical thermostat of claim 16, wherein the controlportion sets the PWM duty to 100% when it is determined that an absolutevalue between the target temperature and the coolant temperature islarger than an upper allowance value.
 18. The control system of theelectrical thermostat of claim 16, wherein the control portion decreasesa PWM duty when the coolant temperature is lower than a targettemperature.
 19. The control system of the electrical thermostat ofclaim 18, wherein the control portion sets the PWM duty to 0% when it isdetermined that an absolute value between the target temperature and thecoolant temperature is lower than a lower allowance value.
 20. Thecontrol system of the electrical thermostat of claim 11, wherein thecontrol portion stops the coolant heating mode before the operatingvalve is opened.